Pump



May 31, 1966 P. B. ZEIGLER ETAL 3,253,548

PUMP

Original Filed Sept. 19, 1958 s Sheets-Sheet 1 w /ffi/aw, 212x 2 49Zia/games B 599% Z? @924? ATTORNEY May 31, 1966 P. B. ZEIGLER ETAL3,253,543

PUMP

Original Filed Sept. 19, 1958 3 Sheets-Sheet 2 $25 k PUMP ,9 Q5

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ATTORNEY United States Patent Philip B. Zcigler, Saginaw, William E.Thompson, Frankeumuth, and Robert P. Rohde, Saginaw, Micln, assignors toGeneral Motors Qorporation, Detroit, Mich, a corporation of DelawareOriginal application Sept. 18, 1958, Ser. No. 762,162. Divided and thisapplication May 27, 1963, Ser. No. 283,298

8 Claims. (Cl. 10342) This application is a division of applicantsapplication Serial No. 762,162, filed September 19, 1958, now abandoned,which was continued as application Serial No. 283,219, filed May 27,1963, now Patent No. 3,027,077. This invention relates to fluid pumpsand in its most specific aspect has relation to constant or fixeddisplacement vane pumps which in use are operated at varying speeds. Thevane pump widely employed in power steering apparatus is exemplary ofpumps of this category, and the invention will be particularly describedwith reference thereto.

Still other problems exist in providing an easily assemblable pumpstructure, relieving parts of the assembled structure of excessivestress during pump operation, maintaining alignment-between pump partsprone to misalignment and guarding against foreign matter accumulationrestricting fluid flow.

An object of the invention is to provide in a vane pump having apressure plate and a thrust plate on 0pposite sides of a cam ringenclosed rotor carrying the vanes with the plates having a pair of portsin circumferential alignment, the cam ring and pressure plate having apair of aligned ports circumferentially spaced from the first-mentionedpair of ports, recesses in the plates facing the rotor communicatingwith the last-mentioned pair of ports, a discharge passage connected tothe lastmentioned pair of ports and an intake chamber surrounding thecam ring open to the first-mentioned pair of ports with the portingarrangement and recesses providing for radial and axial pressure balanceof the rotor.

Another object of the invention is to provide a vane pump having a shaftdriven vane carrying rotor in a cam ring with a plate at each side ofthe rotor with pins extending through the cam ring and plates and abearing supporting the shaft on one plate whereby the pins center theshaft to maintain proper rotor alignment relation to the cam ring andplates to correct for any shaft mounting misalignment.

Another object of the invention is to provide in a pump housing a borehaving located therein a rotor, a pressure plate engaging the rotor anda closure plate spaced from the pressure plate providing a dischargechamber to provide an easily assem blable pump structure with theclosure member being retained by a retaining ring Whose seating force isaided by pump discharge pressure.

Now to identify the accompanying drawings illustrating the invention ina preferred embodiment:

FIGURE 1 is an end elevation;

FIGURE 2 is a sectional View on the line 22 in FIG- URE 1;

FIGURE 3 is a section on the line 3-3 in FIGURE 1;

FIGURE 4 illustrates the relative disposition of certain of the pumpparts;

FIGURE 5 is a generally diagrammatic representation of the flow controland anti-cavitation system and shows a slight modification of the FIGURE2 valve structure; and

FIGURE 6 is a graph reflective of the operation of the pump.

Referring first to FIGURES 1-3, the numeral 10 denotes a reservoirdesirably formed of sheet metal and encircling the pump proper. Thereservoir will be seen as comprising a filler tube 12 having a cap 14.

A seal 16 accommodated in an annular recess in the pump casing 18, whichcarries a mounting piece 19, prevents leakage around the rim portion 20of the reservoir.

Casing 18 is of one-piece construction, with inner and outer recesses 22and 24, respectively. A cover piece 26 is encircled by a seal 28 andshoulders against a snap ring 30, both the seal and ring findingaccommodation in annular recesses formed in casing 18. It is importantto note that due to the rounded contour of cover 26 and the fact thatthe ring 30 is circular in section, the forces subsequently to bementioned which tend to displace the cover 26 outwardly or rightwardly(FIGURE 2) do not tend to shear the ring, as would be the case if itwere of rectangular section. Rather, such forces tend merely to moresecurely seat the ring in its groove. The ring is easily removed whennecessary through the use of a punch inserted through the hole 31.

Extending through a journal boss 32 integral with cast ing .18 is adrive shaft 34 splined at its inner end for opera'ble connection to arotor 36. Outward of the rotor, the shaft, which has an integral flange34a taking thrust loads, is surrounded by a bushing 38 and a seal 40.

Rotor 36 carries a plurality of vanes 42 (note FIG- URE 4) which inoperation of the pump are caused to reciprocate radially in slots 42a bya cam ring 44 Within which the rotor is confined.

A pressure plate 48 at the right side of the rotor (FIG- URE 2) andabutting the cam ring 44 forms a discharge chamber 50 with the cover 26.The inner face of this plate is relieved at 48a. At the opposite or leftside of the rotor and abutting the corresponding side of the cam ring 44is a thrust plate 52 having a recessed portion 52a. As shown, this plateencircles the drive shaft 34 and bears against the wall 54 of the recess22.

Cam ring 44 is supported within the casing 18 by pins 56 (FIGURE 3).Such pins extend through the pressure plate 48 and the thrust plate 52,as Well as the cam ring, and are received within blind bores formed inthe flange portion 18a of the casing 18. Outward of the pressure plate48 the pins serve as guides for springs 58 which react against theinside of cover 26.

A feature of the arrangement involving the dowel pins 56 resides in asleeve 37 preferably press fitted into the rotor 36 and having a closebearing fit with relation to the thrust plate 52. Such sleeve allows therotor to partake of the alignment provided by the dowel pins andcorrects for misalignments of the shaft 34.

Bolts 60, seen in FIGURE 3, secure the reservoir 10 to casing 18.

As illustrated by FIGURES 2 and 5, casing 18 outward of its center lineis bored and counterbored to provide a cavity 85 for the reception of aflow control valve 64. Such valve is biased rightwardly by a spring 66,the limit of the rightward movement being set by a plug member 68 whichis provided with a seal 70 and shoulders against a snap ring 72.

Chamber 50, previously mentioned as formed by pressure plate 48 andcover 26, receives the pump discharge. Such chamber opens to a shortpassage 76, in turn open ing to a relatively long passage 78 of lesserdiameter, these passages providing the connected discharge passage forconveying the pump discharge from chamber 50. Extending from passage 78is a branch discharge passage 80 of much smaller diameter than passage78. Passage 80, which is actually an orifice determinative of the flowrate of the pump, communicates with the pumps outlet or exhaust port andthe fixture 81 seen in FIGURE 3.

As shown by FIGURES 2 and 5, passage 78 opens to a) the previouslymentioned cavity housing valve 64. Also opening to such cavity is apassage 82 extending downwardly from an annular chamber 84 whichsurrounds thrust plate 52, cam ring 44 and the relieved portion 48a ofpressure plate 48.

A passage 86, connecting with pasage 82, is at all times open to thechamber a of the reservoir 10 and constitutes the inlet or intakeport,of the pump. Fluid returned to the reservoir from the system servedthereby enters the reservoir via a tube 89 seen in FIGURE 3. A conduit83 opening to the cavity 85 leftward (FIG- URE 2) of the valve 64connects with the orifice passage 80 as shown in FIGURE 5.

Going now to FIGURE 4, it will be observed that the relieved portion 48aof the pressure plate 48 is of symmetrical free-form outline and thatthe plate is provided with a pair of diametrically opposed openings 90.It is through these openings that the pump discharge passes into thechamber 50. Portions 90a of openings 90 accommodate the previouslymentioned pins 56 affording support to the cam ring 44.

Radial-1y inward of openings 90 are a pair of arcuate openings 92 and apair of arcuate recesses 94 within which are holes 96. The purpose ofopenings 92 is to allow for the passage of fluid at discharge pressurefrom chamber 50 to cavities 98 (located at the innermost reaches ofslots 42a) as the vanes 42 move radially outwardly. This assures properengagement of the outer edges of the vanes with the inner contour of thecam ring 44.

Holes 96 are so placed with reference to the inner contour of cam ring44 that they meter the flow of fluid from cavities 98 to chamber 50 asthe vanes move radially inwardly. In this way, such movement of thevanes is cushioned and the life thereof extended.

The re-entrant portions 100 at the periphery of the relief 48a (plate48) extend inwardly of the adjacent inner edge of the cam ring toprovide intake ports 100a open to intake chamber 84.

From FIGURE 4, it will be observed that thrust plate 52 is supplied withholes 102 allowing for the passage therethrough of the pins 56. Inwardof such holes are recesses 104 conforming in outline with the effectiveportions of Openings 90 in pressure plate 48. These recesses 104 are incircumferential alignment with the openings 90 and communicate therewiththrough the intervane chambers 91 and holes 93 in cam ring 44.Similarly, arcuate recesses 106 are in circumferential alignment witharcuate openings 92 and arcuate recesses 108 are in circumferentialalignment with arcuate recesses 94.

As should be readily apparent, the periphery of thrust plate 52 matchesthat of the relieved portion of 48a of plate 48. Thus, since recesses104 circumferentially register with openings 90 as described, it followsthat the re-entrant portions 110 circumferentially register with thereentrant portions 100. The re-entrant portions 110, like portions 100,extend inwardly of the inner contour of cam ring 44. Accordingly, asecond pair of intake ports 110a leftward (FIGURE 4) of such ring isprovided.

To describe now the general operation of the pump and referringparticularly to FIGURES 2 and 4, with the rotor 36 turning clockwise,fluid is drawn into the intervane chambers 91 from intake chamber 84 viaports g cally opposed relation of the suction and pressure chambers asset by the cam ring maintains the'rotor 36 in radial balance. Lessevident, perhaps, is the fact that the rotor is in substantial axialbalance, this being the purpose of the several recesses or pockets inthrust plate 52. It is to be noted that discharge fluid enteringrecesses 104 passes to chamber 50 via holes 93 in cam ring 44 and ports90 in the pressure plate.

An important feature of the construction of the thrust plate 52 goes tothe recess 52a which permits of slight deflection of the plate from theforce of the fluid pressure to which it is subject. This slightdeflection operates to promote egrees to the intake chamber 84 or thepressure chamber 50 of any foreign matter which might otherwise tend toaccumulate in the recesses in the plate.

The discharge fluid, as aforenoted, leaves the pump via the passage ororifice branching from passage 78. Assuming the pump is being used forpower steering and is operating at minimum speed, i.e., assuming thatthe engine of the vehicle carrying the pump is idling, all of thedischarge fluid normally passes through the orifice 80 and out theconduit 81 to the system, valve 64 under the indicated condition beingin its closed position shown. The flow rate set by the orifice 80 is, ofcourse, a function of the diameter and length thereof. In mostinstallations these factors are calculated to give a flow rate of from2-3 gallons of fluid per minute, such flow rate having been foundsufficient to provide adequate assist with the engine idling and withthe steering resistance maximum, as obtains during parking.

Let it be assumed now that the vehicle carrying the pump is traveling athighway speed. Since the pump rotor is turning at corresponding speed apressure build-up naturally occurs in the chamber because of therestriction 80. As a consequence, valve 64 is displaced leftwardly (FIG.2 and FIG. 5) against the resistance of the spring 66 and the fluid atsystem pressure contained within the spring chamber, so that thepassages 78 and 82 become interconnected. Spring 66, of course, iscarefully selected or gaged to yield under the indicated conditions. Arelief valve, not shown, responsive to the pressure in the springchamber and opening to intake chamber 84 when such pressure reaches apredetermined value is normally included in the system.

As the bypass oil courses passage 82 it attains substantial velocity.Under Bernoulli's principle, the kinetic energy thus developed istranslated in substantial part into static pressure in the chamber 84.Since the magnitude of the static pressure is a function of the velocityin passage 82 and since such velocity is in turn a function of the pumpspeed, cavitation with its undesirable manifestations is effectivelyprevented.

Heretofore, with the pump bypassing as described, the discharge to thesystem rose abruptly at a pump speed of from 3500-4000 r.p.m., note pumpB in FIGURE 6, wherein pump speed is plotted as abcissae and flow rateas ordinates. Such condition, as noted in the forepart hereof, causedexcessive heating of the fluid and the parts in contact therewith. Also,because of the increased flow rate through the system, leakage problemswere prone to occur.

According to the invention, a flow rate is attained as illustrated bypump A in FIGURE 6. Thus, the flow rate is actually caused to fall offinstead of increase at the higher pump speeds. Consequently, there is noheat build-up in the system such as previously experienced. Thisdesideratum is achieved by careful control of the diameters of passages76 and 78 relative to passage or orifice 80. Passage 78 being of lesserdiameter than passage 76, fluid flow therethrough is commensurately morerapid. At a pump speed reflected 'by the graph of FIGURE 6, the fluidflowing through passage 78 begins to have a venturi-like effect withrespect to the opening of the orifice 80 with the result that since thestatic pressure decreases at this point at the same rate as velocitypressure increases according to Bernoullis principle less fluid ispermitted to pass said orifice because of the resulting decrease instatic pressure drop across this orifice than is the case with the pumpidling or operating at speeds reflective of parking conditions or lowspeed travel.

We claim:

1. A pump including a casing having inlet and outlet ports, a cam ringwithin said casing, a rotor within said cam ring carryingcircumferentially spaced vanes, drive means extending into said casingand operably connected to said rotor to rotate the same at varyingspeed, such rotation being accompanied by radial reciprocation of saidvanes induced by said cam ring, a pressure plate within said casing atone side of said rotor and abutting the corresponding side of said camring, a thrust plate within said casing at the other side of said rotorand abutting the corresponding side of said cam ring, said platescomprising re-entrant portions providing a pair of ports incircumferential alignment, said pressure plate and said cam ringcomprising openings in the bodies thereof providing a pair of ports incircumfertial alignment circumferentially spaced from saidfirst-mentioned pair of ports, said plates having recesses facing saidrotor open to said last-mentioned pair of ports, said casing havingtherein a discharge passage to which said last-mentioned pair of portsand said outlet port open, together with a bypass passage and a passageinterconnecting said discharge and bypass passages, and being formed toprovide an annular intake chamber to which said circumferentiallyaligned first-mentioned pair of ports and said inlet port open, and saidintake chamber surrounding said cam ring and communicating with saidbypass passage.

2. A pump including a casing having inlet and outlet ports, said casinghaving a bore with a small, an intermediate and a large diameter portionwith the small diameter portion at one end and the large diameterportion at the other end, a cam ring within said intermediate diameterbore portion of said casing, a rotor within said cam ring carryingcircumferentially spaced vanes, drive means extending through said smalldiameter bore portion into said casing and operably connected to saidrotor to rotate the same at varying speed, such rotation beingaccompanied by radial reciprocation of said vanes induced by said camring, a pressure plate within said intermediate diameter portion of saidcasing at one side of said rotor and abutting the corresponding side ofsaid cam ring and the step between the small and intermediate diameterbore, a thrust plate within said casing at the other side of said rotorand abutting the corresponding side of said cam ring located in saidlarge diameter bore portion, said plates comprising re-entrant portionsproviding a pair of ports in circumferential alignment, said pressureplate and said cam ring comprising openings in the bodies thereofproviding a pair of ports in circumfertial alignment circumferentiallyspaced from said first-mentioned pair of ports, said plates havingrecesses facing said rotor on opposite sides open to said last-mentionedpair of ports, said casing having therein a discharge passage to whichsaid last-mentioned pair of ports and said outlet port open, togetherwith a bypass passage and a passage interconnecting said discharge andbypass passages, and being formed to provide an annular intake chamberto which said circumferentially aligned first-mentioned pair of portsand said inlet port open, said intake chamber surrounding said cam ringand communicating with said bypass passage, and a cover member sealingthe open end of said large bore providing a discharge chambercommunicating with said discharge passage.

3. A pump and fitting assembly including a casing having inlet andoutlet ports, a reservoir within which said casing is housed, saidreservoir being open to said inlet port, a cam ring within said casing,a rotor within said cam ring carrying circumferentially spaced vanes, ashaft extending into said casing and operably connected to said rotor torotate the same at varying speed, such rotation being accompanied byradial reciprocation of said vanes induced by said cam ring, a pressureplate within said casing at one side of said rotor and abutting thecorresponding side of said cam ring, a thrust plate within said casingat the other side of said rotor and abutting the corresponding side ofsaid cam ring, a plurality of pins extending through said ring and saidplates and supported by said casing, a sleeve between said shaft andsaid rotor having a close bearing fit in one of said plates to maintainthe rotor centered with respect to said ring, said plates comprisingre-entrant portions providing a pair of ports in circumferentialalignment, said pressure plate and said cam ring comprising openings inthe bodies thereof providing a pair of ports in circumferentialalignment circumferentially spaced from said first-mentioned pair ofports, said thrust plate and said pressure plate further comprising inthe inner faces thereof recesses of similar outline in circumferentialalignment open to said last-mentioned pair of ports, said casing havingtherein a discharge chamber and a discharge passage to which saidlast-mentioned pair of ports and said outlet port open, together with abypass passage and a passage interconnecting said discharge and bypasspassages, and being formed to provide an annular intake chamber to whichsaid circumferentially aligned first-mentioned pair of ports open, saidintake chamber surrounding said cam ring and communicating with saidbypass passage, said discharge chamber having a cover, spring meansholding said cover and said thrust plate in position.

4. A pump and fitting assembly including a casing having inlet andoutlet ports, said casing having a bore with a small, an intermediateand a large diameter bore portion coaxially located with the smallportion at one end and the large portion at the other end, a reservoirwithin which said casing is housed, said reservoir being open to saidinlet port, a cam ring within said intermediate bore portion of saidcasing, a rotor within said cam ring carrying circumferentially spacedvanes, drive means extending through said small bore portion into saidintermediate portion of said casing and operably connected to said rotorto rotate the same at varying speed, such rotation being accompanied byradial reciprocation of said vanes induced by said cam ring, a pressureplate within said intermediate bore portion of said casing at one sideof said rotor and abutting the corresponding side of said cam ring andthe step between the small and intermediate bore portions, a thrustplate within said large bore portion of said casing at the other side ofsaid rotor and abutting the corresponding side of said cam ring, aplurality of pins extending through said ring and said plates andsupported by said casing, a sleeve between said shaft and said rotorhaving a close bearing fit in one of said plates to maintain the rotorcentered with respect to said ring, said plates comprising re-entrantportions providing a pair of ports in circumferential alignment, saidpres sure plate and said cam ring comprising openings in the bodiesthereof providing a pair of ports in circumferential alignmentcircumferentially spaced from said first-mentioned pair of ports, saidthrust plate and said pressure plate comprising in the inner facesthereof recesses of similar outline circumferentially aligned and opento said last-mentioned pair of ports, a closure closing said large boreportion of said casing to provide a discharge chamber to which saidlast-mentioned pair of ports and said outlet port open, together with abypass passage and a passage interconnecting said discharge chamber andbypass passage, and being formed to provide an annular intake chamber towhich said circumferentially aligned first-mentioned pair of ports open,and said intake chamber surrounding said cam ring and communicating withsaid bypass passage, stop and seal means, spring means biasing saidclosure and pressure plate into position abutting said stop and sealmeans.

5. A pump including a casing having inlet and outlet ports, said casingbeing housed within a reservoir to which said inlet port opens, a camring within said casing, a rotor within said cam ring carryingcircumferentially spaced vanes, drive means extending into said casingand operably connected to said rotor to rotate the same, such rotationbeing accompanied by radial reciprocation of said vanes induced by saidcam ring, a pressure plate within said casing at one side of said rotorand abutting the corresponding side of said cam ring, and a thrust platewithin said casing at the other side of said rotor and abutting thecorresponding side of said cam ring, said plates comprising re-entrantportions providing a pair of ports in circumferential alignment, saidpressure plate and said cam ring comprising openings in the bodiesthereof providing a pair of ports in circumferential alignmentcircumferentially spaced from said first-mentioned pair of ports, saidthrust plate and said pressure plate having recesses in their innerfaces facing said rotor and being in circumferential alignment and opento said last-mentioned pair of ports, said casing having therein adischarge passage to which said last-mentioned pair of ports and saidoutlet port open and being formed to provide an annular intake chambercommunicating with said inlet port and to which said circrunferentiallyaligned first-mentioned pair of ports open, said intake chambersurrounding said cam ring.

6. A pump including a casing having inlet and outlet ports, said casingbeing housed within a reservoir to which said inlet port opens, a camring within said casing, a rotor within said cam ring carryingcircumferentially spaced vanes, drive means extending into said casingand operably connected to said rotor to rotate the same, such rotationbeing accompanied by radial reciprocation of said vanes induced by saidcam ring, a pressure plate within said casing at one side of said rotorand abutting the corresponding side of said cam ring, and a thrust platewithin said casing at the other side of said rotor and abutting thecorresponding side of said cam ring, said plates comprising re-entrantportions providing a pair of ports in circumferential alignment, saidpressure plate and said cam ring comprising openings in the bodiesthereof providing a pair of ports in circumferential alignmentcircumferentially spaced from said first-mentioned pair of ports, saidthrust plate and said pressure plate having 4 therein recesses incircumferential alignment open to'said last-mentioned pair of ports,said casing having therein a discharge passage open to said outlet portwith which said last-mentioned pair of ports and connected said recessescommunicate and being formed to provide an annular intake chamber opento said inlet port and to which said first-mentioned pair ofcircumferentially aligned ports open, said intake chamber surroundingsaid cam ring.

7. In a pump of the class described comprising Within a casing, a camring, a vane-carrying rotor circumscribed by said cam ring, a shaft fordriving said rotor and a pair of plates one at either side of said ring,a plurality of pins extending through said ring and said plates andsupported by said casing, and a sleeve element between said shaft andsaid rotor and having a close bearing fit in one of said plates wherebysaid rotor is maintained in centered relation with respect to said ringby said pins acting through said one plate.

8. A pump comprising a casing, a vane-carrying rotor within said casing,a cam ring circumscribing said rotor and a pair of plates one at eitherside of said cam ring, one of said plates being a thrust plate providedwith a plurality of recesses in its inner face, the other being apressure plate having a plurality of corresponding ports therein, saidthrust plate being subject to the force of fluid at discharge pressureand having a reduced width opposite said rotor provided by a recess inthe outer face of said thrust plate designed to flex slightly from suchforce whereby the removal of foreign matter from said recesses ispromoted.

References Cited by the Examiner UNITED STATES PATENTS 1,326,124 12/1919 Vischer 220-55 2,350,651 6/ 1944 Taubert et a1 220-55 2,649,7378/1953 Hoen et a1 103-136 2,755,741 7/1956 Erskine 103-136 2,759,4238/1956 Keel 103-42 2,809,588 *10/ 1957 Stewart 103-42 2,809,593 10/1957Klessig et al. 103-136 2,858,766 11/ 1958 Toschkotf 103-42 2,880,674 4/1959 Klessig et a1 103-42 2,919,651 '1/ 1960 Gardiner 103-136 3,012,51112/ 1961 Adams 103-42 3,076,414 2/1963 Adams 103-42 5 MARK NEWMAN,Primary Examiner.

LAURENCE V. EFNER, DONLEY J. STOCK'ING, Examiners.

G. M. THOMAS, W. J. KRAUSS, Assistant Examiners.

1. A PUMP INCLUDING A CASING HAVING INLET AND OUTLET PORTS, A CAM RINGWITHIN SAID CASING, A ROTOR WITHIN SAID CAM RING CARRINGCIRCUMFERENTIALLY SPACED VANCES, DRIVE MEANS EXTENDING INTO SAID CASINGAND OPERABLY CONNECTED TO SAID ROTOR TO ROTATE THE SAME AR VARYINGSPEED, SUCH ROTATION BEING ACCOUMPAINED BY RADIAL RECIPROCATION OF SAIDVANES INDUCED BY SAID CAM RING, A PRESSURE PLATE WITHIN SAID CASING ATONE OF SAID ROTOR AND ABUTTING THE CORRESPONDING SIDE OF SAID CAM RING,A THRUST PLATE WITHIN SAID CASING AT THE OTHER SIDE OF SAID ROTOR ANDABUTTING THE CORRESPONDING SIDE OF SAID CAM RING, SAID PLATES COMPRISINGRE-ENTRANT PORTIONS PROVIDING A PAIR OF PORTS IN CIRCUMFERENTIALALIGNMENT, SAID PRESSURE PLATE AND SAID CAM RING COMPRISING OPENINGS INTHE BODIES. THEREOF PROVIDING A PAIR OF PORTS IN CIRCUMFERENTIALALIGNMENT CIRCUMFERENTIALLY SPACED FROM SAID FIRST-MENTIONED